Sol. Solid camphor directly changes into camphor vapour and this process is called sublimation. The sublimation is the process in which some substances upon heating directly changes into vapour from and when cooled again directly turns into solid form.

Sol. Hydrogen gas is used in the manufacturing of Vanaspati ghee. To prepare the Vanaspati ghee, hydrogen gas is passed through vegetable oils under 8-10 atmospheric pressure in the presence of nickel powder at a temperature of 200°C, oil changes into vegetable ghee or solid fat known as Vanaspati ghee.

Sol. Xenon is a chemical gas with symbol Xe and atomic number 54. It is a rare, odourless, colourless, tasteless, chemically unreactive gas. Xenon gas is also known as stranger gas as its volume is low in the atmosphere .